Fluid pump



A ril 24, 1956 o. H. BANKER FLUID PUMP 4 Sheets-Sheet 2.

Filed March 9, 1953 39 fizz/6% 5 dam/115a P 1956 o; H. BANKER 2,742,862

FLUID PUMP Filed March 9, 1953 4 Sheets-Sheet 5 BY Zaw/oz/ZJM WW April24, 1956 o. H. BANKER 2,742,862

FLUID PUMP Filed March 9, 1953 4 Sheets-Sheet 4 JNVENTOR.

FLUID PUMP Oscar H. Banker, Evanston, Ill., assignor to New ProductsCorporation, Chicago, 111., a corporation of Delaware Application March9, 1953, Serial No. 341,272

Claims. (Cl. 103-126) free radial clearance at the internal peripheralsurface of the housing; thereby economizing in cost of manufacture byeliminating a close fit of the around the gears.

A further and more specific object is to provide a gear pump of the sortreferred to above, wherein fixed, hollow, fluid pressure responsivemembers of resilient ma terial are associated in sliding sealingrelation to a side .and/or peripheral surface or surfaces of the pumpgears fectively sealed at the high pressure discharge zone, yet

liberal clearance exists between the unsealed portion of the gears andthe housing pumping cavity other than its discharge zone.

Still another specific object is to provide an improved self-sealing andself-compensating gear pump featuring a resiliently expansible unit insliding sealing engagement with side surfaces of the meshing pump gears,as described above, which unit has an internal pressure cavity ofpredetermined shape and size, substantially overlapping the sidespressure discharge zone adjacent their meshing teeth. The internal areaof a wall of the cavity facing the gears is substantially greater thantheexternal area of the unit which is exposed at the pressure zone, sothat a pressure diiferential is created to maintain the unit in tightsealing engagement with the gear side surfaces, for the purposesdescribed in the preceding paragraphs.

A still further object is to provide an improved gear pump of the sortdescribed above featuring, in certain embodiments thereof, a shapeddischarge throat or dis charge member of resilient material adjacent thepump discharge opening, the member being shaped to provide of the gearsoutwardly of a high' arcuate gear tooth sealing shoulders positioned forra dial wiping and sealing engagement with the teeth of the pump gears,over a substantial arc in each case. The shoulders are thrust intoradial sealing relation gears by the discharge pressure, which is inmost inment with the gear housing of the pump.

Yet another object is to provide a self-sealing gear pump incorporatinga radially acting, gear tooth sealing member in combination with a gearside surface sealing member, both members being urged to sealingengagement with the gears by pressure equal to the pump dischargepressure at the meshing gear teeth zone.

A further object is to provide a pump which, in other modificationsthereof, has arcuate concave tooth sealing shoulders thrust into gearteeth under the plied discharge pressure at the high pressure zone.

In still another modification, peripheral gear tooth sealing action isperformed by a pair of laterally spaced, internally chambered, concavesurfaced sealing shoulders which occupy opposed corners of the housinginterior; the shoulders are urged into engagement with the teeth byinternal pressure equal to the pump discharge pressure.

Yet another embodiment according to the invention contemplates the useof an arcuate gear tooth sealing shoulder member or members yield-ablyurged radially against the gears by an adjustable spring biasingarrangepressure regulator, by enabling the sealing member or members toyield at a desired pre-set spring setting and thus by-pass liquid fromthe high pressure discharge zone, of the pump cavity. I

In any of the embodiments, it is an object to provide a gear pump asdescribed in the preceding paragraphs in which the sealing members whichengage the pump gears, particularly the radially acting members, may bemetal clad to resist wear on the gear engaging surface or surfaces, andto prevent jamming into the gear teeth. Use of such wear means may bedispensed with in low pressure pumps, but is practically indispensibleinheavy duty types.

The foregoing statements way of the nature of the invention. Other andmore specific objects will be apparent to those skilled in the art upona full understanding of the operation of the improved pump.

Various modified embodiments of the invention are presented herein forpurpose of illustration. It will be appreciated that the invention maybe incorporated in still other modified forms coming equally within thescope of the appended claims.

In the drawings:

Fig. 1 is a side elevational view of the improved pump, in accordancewith one embodiment thereof;

Fig. 2 is a view in longitudinal cross section along a line generallycorresponding to line 2-2 of Figs. 1 and 4, generally showing thelateral sealing member for the pump gears;

Fig. 3 is a cross sectional view through the pump on line 3.3 of Fig. 2,illustrating details of the'improved, side-acting gear sealingarrangement, and of the discharge side of the pump;

Fig. 4 is a view in transverse section along line 4-4 of Fig. 3, furthershowing the improved discharge throat sealing provisions of theinvention;

are indicative in a general construction and p Fig. is a view in frontelevation of the side gear surface sealing member of the improved pump,the member being viewed as from line '5-5 of Figs. 2 and 3;

Fig. 6 is a view in transverse section, similar to Fig. 4, showing ametal clad discharge throat sealing member in accordance with a slightlymodified adaptation of the invention;

Fig. 7 is a view in'transverse vertical section, partially broken away,and approximately as viewed along line '7-7 of Fig. 8, illustrating pumphousing components of a modified form of the invention, particularly asregards the radially acting gear tooth sealing provisions adjacent thepump discharge side;

Fig. 8 is a view in vertical longitudinal section along a linecorresponding to line 8-8 of Fig. 7;

Fig. 8A is a view in vertical section along1ine8A-8A of Fig. 7;

Fig. 9 is a view similar to Fig. 7, and as viewed along line 9-9 of Fig.10, showing a further'modified embodiment of the invention involving ablock-like discharge throat sealing device;

Fig. 10 is a view in longitudinal vertical section approximately alongline 10-40 of Fig. 9;

Fig. 11 is a view in transverse section, along a line corresponding toline 1'111 of Fig. l2,illustrating yet another modified embodiment ofthe invention, featuring laterally spaced, radially acting gear teethsealing shoulders;

Fig. 12 is a view in line 1212 of Fig. 11;

Fig. 13 is a view generally similar to Fig. 11 showing a still furthermodified form of the invention, featuring an adjustable spring pressureregulating action at the radially acting gear tooth sealing surfaces;and

Fig. 14 is a view in vertical longitudinal section along a linecorresponding to line 1'4-14 of Fig. 13.

Although the above figures disclose pumps of a wellknown sort havinggears with external meshing teeth, the principle of the invention isalso adaptable to a gear pump of the outside-inside type, featuring alarger, internally toothed gear and a smaller, externally toothed gearin mesh therewith.

Referring to Figs. l-6 inclusive, ofthe drawings, the reference numeral10 generally designates a housing or casing for the improved pump inaccordance with one form of the invention. It consists of anappropriately chambered gear housing and intake-discharge passage memberor body 1 1, at'the'right, having intake and discharge fittings 12, 13,respectively, communicating with its interior at vertically spacedlevels. closure and bearing plate 14, at the left, is bolted to housingbody 11.

Housing 10 provides a pump gear cavity 15 to which liquid is suppliedthrough an intake passage 16 in' alignment with intake fitting 12.Meshing pump gears 17, 18 are located in this cavity, their shafts '19being journalled by roller bearings in bearing receiving openings 20 ateither side of the gear cavity. Appropriate cages mount the bearings inthe openings, in well known fashion.

It will be noted, particularly by reference to Fig. 4, that asubstantial radial clearance exists between the outer extremities of theteeth of gears "17, 18 and the inner peripheral wall of housing cavity'15. Close tolerance machining and fitting of parts is thus eliminated.The pump is driven through a shaft 21 on gear 18, as illustrated in Fig.2, leakage at this point being prevented by the use of a conventionalseal 22.

In accordance with this form of the invention, and as best illustratedin Fig. 4 of the drawings, the teeth of longitudinal vertical sectionalong gears 17, 18, adjacent the central, restricted, discharge zone orspace Z of pump chamber 15, have sliding,.pressure sealing engagementwith laterally spaced arcuate shoulder surfaces 23 of a discharge throatinsert 24 of special shape and non-metallic composition. Referring Anend or side to Figs. 3 and 4, insert 24 is provided with an intakethroat 25 between shoulder surfaces 23, which throat opens downwardlyfrom high pressure discharge zone Z. Throat 25 communicates downwardlywith an enlarged, generally cylindrical interior 26 of insert 24, andthis space in turn opens laterally, through a port 27 of substantialsize in the insert, to a discharge passage 28 in housing body 11. Theinsert 24 is an elastomer unit fabricated of rubber or like elastic orrubber-like material and is snugly fitted in a recess in the body whichdownwardly adjoins its gear pumping chamber 15. Other gear side sealingmeans, to be described, coact with insert 24 in the automatic,self-pressurized sealing of gears 17, 18 in accordance with theinvention. However, a description of the rest of the pump body structurewhich adjoins the discharge passage 28 appears in order in the interestof continuity. Illustration and description of such structure aredispensed with in connection with the other modifications shown in Figs.7-14, but it is to be understood that similar provisions will beassociated with those forms.

Housing body 10 is provided, in alignment with the passage 28, with anenlarged cylindrical bore 29 to which the passage opens. This borereceives a fixed tubular valve insert sleeve which'is generallydesignated 30. The insert has a plurality of radial ports 31 leading toa transverse by-pass duct 32 in the body, by which excess liquid may bereturned to intake passage 16. This is done under the control of ahollow, centrally apertured pressure regulator plunger 33 slidablymounted in the valve sleeve 30.

Plunger 33 is adapted to yield rearwardly against the force exerted byits internal biasing spring 34, exposing radial ports 31 so that-part ofthe liquid is by-passed back to the pump intake under a condition ofexcess pressure.

Valve 'sleeve has a further radial passage or passages 35 and an annulargroove, whereby its hollow interior is communicated with a transversepressure relief passage 36 in the valve body. Emergency flow of liquidthrough'passage 36 to intake passage 16 is controlled by a ball check37; this is held in sealing position by a biasing spring 37 encircling astem 38 threadedly engaged with housing body member 11. The force ofspring 37' exceeds that of plunger biasing spring 34-. Ported valvesleeve 30 is sealed in bore 29 by annular Orings in known fashion, andthe sleeve is held in place in the bore by a split snap ring 40.

The normal discharge flow of the pump is through passage 28, a centralaperture 39 in the inner radial face of plunger 33 and the plungerinterior, to discharge fitting 13, being regulated and controlled by theplunger check valvea'nd by-pass means just describcd.

As indicated above, there is associated with the resilient dischargethroat insert 24 further means to provide aside sealing of the gears 17,18; such means takes the form of a plate-like unit, generally designated41, which is best illustrated, per se, in Figs. 2, 3 and 5 of thedrawings. Its relation to the gears and insert 24 is also indicated in'Fig. 4.

Unit '41 comprises a flat metallic wear plate or disk 42 shaped ingeneral conformity with the outline of the gear cavity 15, as can beseen by comparing Fig. 5 with Fig. 4. An'approximately semi-circularnotch 43 is formed at the upper center of this member to fully exposeintake passage 16 to the pump cavity. A hollow pressure responsivemember 44 of molded rubber, or other elastic, rubber-like'material isfitted in a correspondingly shaped recess in the rear of plate 42, andmay be vulcanized thereto. Plate 42 is provided with laterally spacedcir cular openings 45 adapted to receive bushings 46 (see Figs. 2 and 4)in which the gear shafts 19 are received. These bushings laterallyconfine the member 44 against the inflativeforce normally present in itsinterior, as it is otherwise-confined by the plate recess.

Member 44 is small in relation to the area of the associated plate 42.It is specially molded inan'outline like that shown'best in Fig. 5. Itis ofrelatively small "internal volume, for quick pressurization;nevertheless, it is of sufiicient size that its forward wall 49 whichhas surface engagement with plate 42' will exert'force on the latterover an area laterally overlapping the side surfaces of gears 17, 18substantially, as shown in Fig. 4, i. e., laterally outwardly ofpressure zone -Z.' =.-'Discharge pressure is communicated with theinterior 48' of 'the sealing unit pressure member 44 through asmallopening 50 in plate 42 and the wall 49 of member'44. t

It is seen from the foregoing :that a differential exists between thehydraulic force of the-discharge. pressure zone Z, acting in a directiontojurge unit 41. away from the gears 17, 18, and an opposite-force,attributable to the same pressure and acting within-member 44 to urgeplate 42 into sealing engagement withthe gear surfaces. The greater areais exposed to'the discharge pressure; it increases as thedischargepressure of the pump increases. The rear wall of member-44isleft mostly open for molding'purposes, but the internal pressure on arear inturned perimetral lip 51 is sufficient to insure against zone,which inany event would not be particularly objectionable, maintainingthe member firmly against the surface of casing body'll whichit-rearwardly abuts v V I. Figs. 3 and 4 of the drawings show that-thedischarge pressure zone Z is defined by the' casing end plate 14,theplate 42 of side unit.41,:and the vertical space between the fullymeshed gear teeth, at the top of the zone, and the teeth which wipe-past the shoulder surfaces 23 of throat insert 24. The pressure inthroat insert 24 continually urges the sealingshoulders' 23 against theperipheral surfaces of the gear teetht It alsocontinually the insert,specially designated 52 and 53' in Fig. '3, against the'casing end platel4a'nd body 11, respectively. There-is thus a dual hydraulic pressureacting at the verticaloverlap of insert 24 and side sealing unit41,:preventing leakage at this overlap area. 7 v

.The improved pump is eflicient in operation and very economical tomanufacture. HandI-cranking alone, of its power input shaft has producedan instantaneous discharge a'ta pressure as high as 50gpounds per squareinch. In an actual run it was found that'operating pressure withinmember 44 causes" itsouter -walls to bulge-and thereby exert greater,wedge-like force on the 'outer portions of the wear plate 42.: Thisseals'the gears even more effectively than the direct central transverseforce. Furthermore, since the gears are free andclear'in cavity 15except at zone Z, a back pressure-cannot be built up to effectivelyoppose the pressure at the sealed area. Throat insert 24 is shown inFig. 4-as a one-piece, unsheathed elastic unit, its shoulder 23in'idirect contact with gear'teeth 17, 18. This is satisfactory for lowpres sure pumping. However, metal ear-elements'should be bonded to theshoulder surfaces for high pressure, heavy duty performance, and Fig. 6shows such a sheathed insert, here designated 24', the wear plates beingnumbered 54. In other respects,the unit'24' is assembled with other pumpcomponents in the identical way described above and shown in Figs. 1hence it is not deemed necessary to repeat the illustrationordescription. It may be assumed that the-insert 24 shown in Figs. 3 and 4represents companion insert 24, in its intended setting in a comparablehigh pressure or heavier duty pump. Corresponding parts are designatedby corresponding reference numerals, primed. V Figs. 7 and 8 show amodified adaptation of the principle of the invention, particularly'as'it relatesto the peripheral sealing of the gear teeth of apump'adjacent its discharge, high pressure throat zone or space. relatedprovisions have been omitted from Figs. 7 and 8 for; the sake ofsimplicity. It maybe :assumed that if such provisions are desired, theymay takethe form illustratedin Figs. 2 and 3 of the drawings. The sameis true of the other modifications illustrated in Figs. 9 and 10, inFigs. 11 and 12, and in Figs. 13 and 14, respectively.

Referring to Figs. 7, 8 and 8A, a hollow, chambered casing body 55 andend plate 56 enclose a shaped pumping cavity '57 in which pump gears 58,59 are rotatively mounted, in an entirely conventional Way, or asillustrated in Fig. 2. A metallic side sealing plate 60 engages onesurface of gears 58, 59, and a resilient cushion disk 60' is interposedbetween plate 60 and casing end plate 56. Plate 60 is shaped inconformity with the upper contour of a block-like metallic sealingmember 61 of width slightly greater than the gears, and fits above thatblock in face engagementwith the gears. It serves as a radial spacer forsealing block 61 as well as a surface wear member, as will be described.Sealing member 61 is provided with arcuate sealing shoulders 62, acrosswhich the teeth of gears 58, 59 wipe over a considerable angular sweep;and the shoulders 62 are spaced on opposite sides of a downwardlyextending pressure passage 63 in member 61. Passage 63 verticallycommunicates the high pressure discharge zone- Z in pumping cavity 57with a pressure plunger cylinder 64 formed at the bottom of pump body55, in vertical alignment with the intake passage 65 to the cavity 57. Acupped plunger 66 and leather anti-extrusion disk 67 act upwardly inthis cylinder against the lower surface of sealing member 61. Ifdesired, a coil compression spring 68 may be provided to supplementhydraulic pressure in cylinder 64 urging the plunger and member61'upwardly.

The side of the pump cavity 57 opposite shaped wear plate 60 is recessedat 71 for the reception of a hollow resilient, rubber-like pressuremember 69 which is generally similar in structure to member 44 of unit41. A metal, gear face wear plate 70 which, like plate 60, is shaped inconformity with the upper surface of sealing block 61, is disposedinwardly of member 69. Plates 60 and 70 are both fitted above theshoulder surfaces 62 of member 61 and are received on the bushings 79',so that in sealing the side surfaces of gears 58, 59 they at the sametime act as spacers to limit the upward travel of sealing block 61 inradially sealing the gear teeth, as shown in Fig. 8A.

Radial tooth sealing block 61 is milled to provide a groove 73 openinglaterally to the discharge passage 72 of easing body 55. Communicationis sage through an opening 74 in hollow pressure member 69.

' The operation of the embodiment of Figs. 7 and 8 is believed to beobvious, in the light of the description in connection with Figs. 1through 6. Plates the side surfaces of the gears portion and at itslower portion bears against the side of sealing block member 61 toassist in scaling in this area. Discharge pressure in zone Z iscommunicated through passage 63 to the cylinder 64 beneath the sealingblock, urging the same upwardly. Coil spring 68 maintains sealingaction, as when the pump is not in operation, or at very low pressureoperation in which the peripheral engagement of the gear teeth withconcave shoulders 62 may not be sufficient to insure sealing at thesesurfaces.

The form of the invention illustrated in Figs. 9 and 10 putstheprinciple of the invention into practise in a slightly different waythanthe forms illustrated and de scribed above. That is, internal hydraulicpressure on a sealing member which acts radially against the peripheriesof the gear teeth is replaced by hydraulic discharge pressure actingexternally on an elastically deforma able sealing member. This causesthe concave tooth sealing shoulder surface or surfaces of such member tomold themselves more tightly to and sealingly engage the outer toothsurfaces. The form of Figs. 9 and 10 is primarily intended for lowpressure pumping, in which the danger of jamming an elastic .sealingsurface in the :gearteeth is :not present.

Referring to Figs. 9 and 10, a side wear plate '76 and a side wear.plate and sealing unit 77 are associated 'with opposite sides of a pairof meshing gears 78, 79 sin a pumping cavity 80. The cavity is definedby a casing body 81 and end plate 82, much in thesame way asshown inFigs. .2 and 3; further illustration and description in this regard canbe dispensed with. The gear engaging wear plate of unit 77 is designated83; its hollow, resilient pressure member is designated :84.

A solid, elastomer thrust block 85 is employed to exert peripheralsealing action on the teeth of gears 78, .79. This type sealing member,in a crescent-shaped outline, may also be used as a sealing unit in aninsideoutside type gear pump molding itself .to and wiping against theexternal and internal meshing gear teeth under the discharge pressure ofthe pump.

-As shown, member -85 is molded in block-like outline of an elastic,flowable material, such as rubber, synthetic rubber and the like, and arigid metallic backing plate 86 rearwardly sustains the same. The thusconstituted sealing unit'is received in a bottom recess 87 adjoiningpumping cavity 80 which is coextensive with the width of the gears.Elastic block 85 is laterally engaged at its sides, as-are the gears 78,79, by the side plate 76 and the plate 83 of pressure unit 77.

Resilient sealing block 85 has concave shoulders 88 in peripheral wipingengagement with the teeth of gears 78, 79, those shoulders being underslight initial compression to seal against static leakage or leakage orvery low pressure operation. The block is also formed to provide amedial recess 89 between these shoulders, in axial alignment with thedischargepassage of housing body 81.

The inherent fiowability or moldability of the material of sealing block85, under the compression of the discharge pressure in zone Z, enablesthe shoulders 88 to maintain effective sealing engagement with the gearsurfaces when the pump is in operation. The block molds itself snugly tothe tooth periphery for this purpose. However, this arrangemcnt is bestsuited for low pressure pumping installation, for if the'elasticmaterial of block 85 is excessively compressed it tends to jam into thespace between the teeth, or else to wear at an unduly high rate.

The embodiment of the invention illustrated in Figs. 11 and 12 adoptsthe principle of an internally pressurized gear tooth sealing unitconstruction, as in forms of Figs. 1 through 6 and Figs. 7 and 8, but ina somewhat different setting. Here a pair of separate, laterally spaced,metallic sealing shoulders 90 are disposed, respectively, at oppositebottom corners of a pump gear cavity 91 in a pump casing 92, the cavitybeing closed by an end plate '93. A side sealing plate 94 is interposedbetween end plate 93 and the meshing gears 95, 96, and a sidepressure-sealing unit 97 is disposed in sealing relation to the oppositeside surfaces of the gears. Unit 97 is composed of a wear plate 98 and ahollow resilient member 99, both located ina recess in casing body 92,as in the last described em bodiment of the invention.

Each of the rigid metal sealing shoulders '90 is shaped to provide anarcuate sealing surface 100 :of substantial length, a rear cornerpressure cavity '101, and a horizontal passage 102 leading to thatcavity from a high pressure discharge zone Z of the pumping chamberv9-1. I A cup "plunger or disk 103 is disposed in the pressure cavity101 to seal the latter when it is pressurized, the disk :beingrearwardly engageable against the side wall of the pump chamber 91 underthis condition. Shoulder members 90 are thus thrust laterally intoengagement with the teeth of gears 95, '96 for the desiredsealingaction. The shoulders-are laterally engaged, along with gears 95, 96, bythe side wear plates 94, 98, as in the preceding embodiment.

The further modified adaptation of the invention illustrated in Figs. 13and l4incorporates an improved pressure regulator feature enabling thepump to be set for a predetermined-maximhmpressnre discharge, and :toby. pass .pressuretabove this critical ,pre-set pressure so that thetoutpu'tiof the pumpiis uniform in this regard. .In this form ablock-like, tooth periphery sealing element :memher 104 is provided,which is fabricated of rigid metallic material. lit isdtaped to. providespaced arcuate shouiders 105 engaging :the teeth of gears 106, 107mounted .for rotation in-agpunping-cavity .108 provided by easing body.109 and end'plate 110.

Member 104 is urged zfor radial sealing engagement by a regulator springunit, generally designated 111, to be hereinafter'described. {It ,is:sealingly engaged at one side thereof 'bya wear plate 112 and at theother side thereof by :the pressure sealing unit 113. Unit 113 iscomposed of afurther wear plate. :114 and a hollow, resilient,nonmetallic member 115,'rmd is practically identical to the sealingunits 77 vand9r7 previously described.

Regulator spring unitldl comprises a vertically di'sposed tubular springhousing 116 having an upper,-reduced diameter extension 1'17 which isthreadedly mounted in the lower sideofthe body 109 of the gear casing,in vertical alignmentwith the center of the pumping cavity 108.Astana-1'18 slidahly received in the bore of ex tension 1177, an D ring119 being mounted in a groove in the stemitn engage the bore for sealingpurposes.

A flanged sleeve or collar 120 is threaded on stem 118 within springhousing .116, and a coil spring 121 upwardly abuts against thefiange ofsleeve 120. This spring is rearwardly sustained by an adjustable nut 122threaded in vthe lower end-of housing 116. Stem 1=18has at Kent 123 inits lower :end by. which it may be rotatively adjusted.

The compression of spring 121 may be pre-set as desired by screwingstemq118 in sleeve 120, whereby the latter exerts, through the forceonisealing member 104. This predeterminedly urges the member against theteeth of gears 106, 107. When the hydrauliepressure in discharge zone Zacting on memher 104 passes acritical, predetermined value, it displacesthe latter downwardly against the preset force of spring- 12-1, andapart of the liquid is by-passed between the gear teeth and the sealingsurfaces 105 to the intake side of 'pump cavity at the desired value,regulated as desired by appropriate adjustment of the spring force.

Thus a pressure regulator feature is incorporated in agear-pump havingthe improved sealing provisions of the invention Asia the case of all ofthe various embodiments illustrated and. described, a gear pump .isprovided which is automatically sealed by simple means which eliminate'the'need-for close tolerance machining andinterfitting of parts. Yethigh pressures are developed at relatively low speeds of gearrotation.Hence the pump may be designed in small and very compact sizes to dowork heretofore-considered to be satisfactorily done only bylpumps =ofmaterially greater cost, both as regards inputand the cost ofmanufacture in an adequately large size for a-specified job- It -isevident that theapressure regulator feature shown in Figs. .13 and 14may also be afforded in the embodiment of the pump shown in Figs. 7 and.8. In such an arrangementthe dome of the spring should be onlysufficient to create-a balance of the opposing forces in zone 1 and inthe plunger cylinder. .ShOl'lld the discharge pressure acting to urgethe sealing throat toward the gears become excessive,representinganundue load on a shaft or bearing, the etfectcanbeotfset bya reversal of rotationof the gear. The intake then becomes a dischargeand the force of the spring, now opposed by discharge pressure, can beset to-produce the desired radial force.

I claim:

.1. A geanrmlmp pumping earthy-and having intake and discharge passagescommunicating :with amid rcavity tatalily mounted i'n the latter, saidcavity having a dis :stem, a desired upward spring- 108.. ,Thismaintains discharge pressure comprising a housing providing a" andmeshing gears ro-' charge pressure zone remote from said intake passage,which zone opens to said discharge passage, a discharge sealing-unitpartially defining and subject to pressure in said zone, saidunit'including a sealing member provided with a sealing surfaceyieldably engaging the peripheries of gear teeth approaching said zone,and means for effecting a seal between said member and the side surfacesof the gears, said means including discharge pressure responsive meansassociated with said member to maintain said member in sealingengagement with respect to said housing whereby said discharge pressurezone is effectively sealed.

2. A gear pump comprising a housing providing a pumping cavity andhaving intake and discharge passages communicating with said cavity andmeshing gears rotatably mounted in the latter, said cavity having adischarge pressure zone remote from said intake passage, which zoneopens to said discharge passage, a discharge sealing unit partiallydefining and subject to pressure in said zone, said unit including asealing member provided with a sealing surface yieldably engaging theperipheries of gear teeth approaching said zone, and means for effectinga seal between said member and the'side surfaces of the gears, saidmeans including discharge pressure responsive means associated with saidmember to maintain said member in sealing engagement with respect tosaid'housing, and a further sealing member maintained by saiddischargepressure in sealing engagement with the side surfaces of said gearswhereby said discharge pressure zone is effectively sealed.

3. A gear pump comprising a housing providing a pumping cavity andhaving intake and discharge passages communicating with said cavity andmeshing gears rotatably mounted in the latter in loose fitting relationthereto, said cavity having a discharge pressure zone remote from saidintake passage, which zone opens to said discharge passage, a dischargesealing unit partially defining and subject to pressure in said zone,said unit including a sealing member provided with a sealing surfaceyieldably engaging the peripheries of gear teeth approaching said zone,and means for effecting a seal between said member and the side surfacesof the gears, said means including discharge pressure responsive meansassociated with said member to maintain said member in sealingengagement with respect to said housing, and a further sealing membermaintained by said discharge pressure in sealing engagement with thesides of said gears whereby said discharge pressure zone is effectivelysealed.

4. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, and opposed side walls in sealing engagement withthe sides of said gears, one of said side walls including deformabledischarge pressure responsive means to urge a side surface of said unitin sealing engagement with the opposite side wall whereby said highpressure discharge zone is effectively sealed.

A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, and opposed side walls in sealing engagement withthe sides of said gears, one of said side walls including deformabledischarge pressure responsive means to urge a side surface of said unitin sealing engagement with the opposite side wall, said means comprisinga hollow member of resilient material having a pressure wait facing saidgear side surfaces which is of an area suflicient'to overlap said gearsurfaces radially outwardly of said meshing gear teeth, said meanshaving an opening through said pressure wall communicating the interiorof said hollow member with said high pressure zone to impose thedischargepressure of said zone on a part of said pressure walloverlapping said gear side surfaces and thus urgesaid last side wall insealing relation to said vgear side surfaces whereby is effectivelysealed.

6. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a highpressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit pro.- vided with asealing'surface in yieldable engagement with the peripheries of gearteeth approaching said zone, and opposed side walls in sealingengagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unit in sealing engagement with the opposite sidewall,said means comprising a hollow member of resilient material having apressure wall facing said gear side surfaces, said pressure wall havingan opening therethrough communicating the interior of said hollow member with said high pressure zone, said last mentioned side wallconstituting a rigid, plate-like wear member interposed between saidgear side surfaces and said pressure wall and substantially overlappingsaid gear side surfaces adjacent said pressure zone whereby said highpres-- sure discharge zone is effectively sealed.

7. A gear pump comprising a pump casing providing a'pump cavity havingmeshing gears rotatable therein and having intake and discharge'passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit pro vided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, said unit provided with means for urging saidsealing surface into sealing engagement with the peripheries of saidgear teeth, and opposed sidewalls in sealing engagement with the sidesof said gears, one of said sidewalls including deformable dischargepressure responsive means to urge a side surface of said unit in sealingengagement'with the opposite'side wall whereby said high pressuredischarge zone is efiectively sealed.

8. A gear pump comprising a pump-casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, said unit provided with discharge pressurereceiving means for urging said sealing surface into sealing engagementwith the peripheries of said gear teeth, and opposed side walls insealing engagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unit in sealing engagement with the opposite side wallwhereby said high pressure discharge zone is effectively sealed. I

9. A gear pump comprising a pump casing providing a pump'cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further'defined by a unit pro-' vided with-asealing surface in yieldable engagement with the peripheries of gearteeth approaching said zone, said unit provided with discharge pressurereceiving means said high pressure discharge zone having associatedtherewith resilient means for urging said sealing surface into sealingengagement with the peripheries of said gear teeth, and opposed sidewalls in sealing engagement with the sides of said gears, one of saidside walls including deformable discharge pressure responsive means tourge a side surface of said unit in sealing engagement with the oppositeside wall whereby said high pressure discharge zone is effectivelysealed.

10. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, said unit provided with resilient means urgingsaid sealing surface into sealing engagement with the peripheries ofsaid gear teeth, and opposed side walls in sealing engagement with thesides of said gears, one of said side walls including deformabledischarge pressure responsive means to urge a side surface of said unitin sealing engagement with the opposite side wall whereby said highpressure discharge zone is effectively sealed.

11. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and :having intake and dischargepassages communicating therewith, .said gears in part defining a highpressure discharge zone of said cavity at the meshing teeth thereof,said discharge zone being further defined by a unit provided with 'asealing surface in yieldable engagement with the'peripheries of gearteeth approaching said zone, said unit provided with resilient means andhaving limiting means associated therewith for urging said sealingsurface into sealing engagement with the peripheries of said gear teeth,and opposed side walls in sealing engagement with the sides of saidgears, one of said side walls including deformable discharge pressureresponsive means to urge a side surface of said unit in sealingengagement with the opposite side wall whereby said high pressuredischarge zone is effectively sealed.

' 12. A gear pump comprising a pump casing providing a pump cavityhaving meshing gears rotatable therein and having intake and dischargepassages communicating therewith, said gears in part defining a highpressure discharge zone of said cavity at the meshing teeth thereof,said discharge zone being further defined by a unit provided with asealing surface in yieldable engagement with the peripheries of gearteeth approaching said zone, and opposed side walls in sealingengagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unitlin sealing engagement with the opposite side wallwhereby said high pressure discharge zone is effectively sealed, saidside walls adapted to limit the extent of engagement brought aboutbetween the sealing surface of said unit and the peripheries of saidgear teeth.

13. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith,'said gears in part defining a highpressure'discharge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, said unit provided with discharge pressurereceiving means for urging said sealing surface into sealing engagementwith the peripheries of said gear teeth, and opposed side walls insealing engagement with the sides of said gears, one'of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unit in sealing engagement with the opposite side wallwhereby saidhigh pressure dischargezone iseffectively sealed, said sidewalls cooperating with said sealing surface to limit the extent ofengagement brought about between said sealing surface and theperipheries of said gear teeth.

14. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a sealingsurface in yieldable engagement with the peripheries of gear teethapproaching said zone, said unit provided with discharge pressurereceiving means having associated therewith resilient means for urgingsaid sealing surface into sealing engagement with the periphcries ofsaid gear teeth, and opposed side walls in sealing engagement with thesides of said gears, one of said side walls including deformabledischarge pressure responsive means to urge a side surface of said unitin sealing engagement with the opposite side wall whereby said highpressure discharge zone is effectively scaled, said side wallscooperating with said sealing surface to limit the extent of engagementbrought about between said sealing surface and the peripheries of saidgear teeth.

15. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by an elastomer unit provided witha sealing surface in yieldable engagement with the peripheries of gearteeth approaching said zone, and opposed side walls in sealingengagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface-of said unit in sealing engagement with the op posite side wallwhereby said high pressure discharge zone is effectively sealed.

16. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a rigid metallic unit providedwith a sealing surface in yieldable engagement with the peripheries ofgear teeth approaching said zone, and opposed side walls in sealingengagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unit in sealing engagement with the opposite side wallwhereby said high pressure discharge zone is effectively sealed.

1?. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit including a pair ofarcuate, concave surfaces in yieldable engagement with theperipheries ofgear teeth approaching said zone and being in outwardly concentricrelation vtothe peripheries of said teeth, and opposed side walls insealing engagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unit in sealing engagement with the opposite side wallwhereby said high pressure discharge zone is effectively sealed.

1%. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone oflsaid cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit comprising a pair ofarcuate, concave surfaces in yieldable engagement with the peripheriesof .gear teeth approaching said zone and being in outwardly concentricrelation to the peripheries of said teeth, the innermostends of saidsurfaces defined by upwardly projecting lips separated by anindentation, said lips adapted to be flexed into sealing engagement withsaid gear teeth in response to discharge pressure, and opposed sidewalls in sealing engagement with the sides of said gears, one of saidside walls including deformable discharge pressure responsive means tourge a side surface of said unit in sealing engagement with the oppositeside wall whereby said high pressure discharge zone is effectivelysealed.

19. A gear pump in accordance with claim 15, in which said unit is ofhollow cup-like form and has openings communicating the interior thereofwith said discharge pressure zone and discharge passage.

20. A gear pump in accordance with claim 15, in which said unit is ofhollow cup-like form and has openings communicating the interior thereofwith said discharge pressure zone and'discharge passage, and a rigidexternal metal sheath mounted on the sealing surface thereof forengagement with said gear teeth.

21. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit including a rigidmetallic member provided with an arcuate sealing surface for yieldablesealing engagement with the peripheries of gear teeth approaching saidzone, said member having an internally positioned deformable means incommunication with said pressure zone to move said member into sealingengagement with said gear teeth in response to discharge pressure, andopposed side walls in sealing engagement with the sidesvof said gears,one of said side walls including deformable discharge pressureresponsive means to urge a side surface of said unit in sealingengagement with the opposite side wall whereby said high pressuredischarge zone is effectively sealed.

22. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit including a pair of rigidmetallic members each positioned to one side of said zone and eachprovided with an arcuate sealing surface for yieldable sealingengagement with the peripheries of gear teeth approaching said zone,each of said members having an internally positioned deformable means incommunication with said pressure zone to move said member into sealingengagement with said gear teeth in response to discharge pressure, andopposed side walls in sealing engagement with the sides of said gears,one of said side walls including deformable discharge face of said unitin sealing engagement with the opposite side wall whereby said highpressure discharge zone is effectively sealed.

23. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of saidcavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a pair ofarcuate, concave sealing surfaces in yieldable engagement with theperipheries of gear teeth approaching said zone and being in outwardlyconcentric relation thereto, said unit provided with means for urgingsaid sealing surfaces into sealing engagement, said means including anelastically deformable member pressure responsive means to urge a sidesur- 14 behind said unit communicating with said pressure zone, andopposed side walls in sealing engagement with the sides of said gears,one of said side walls including deformable discharge pressureresponsive means to urge a side surface of said unit in sealingengagement with the opposite side wall whereby said high pressuredischarge zone is effectively sealed, the bottom edges of said sidewalls resting on said sealing surfaces to limit the extent of engagementbrought about between said surfaces and the peripheries of said gearteeth.

24. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit provided with a pair ofconcave arcuate sealing surfaces adapted to engage the peripheries ofgear teeth approaching said zone, a plunger, means for moving saidplunger into contact with said unit to move the sealing surfaces thereofinto engagement with the peripheries of said gear teeth, resilient meansfor resisting movement of the sealing surfaces and plunger away from theperipheries of said gear teeth, and opposed side walls in sealingengagement with the sides of said gears, one of said side wallsincluding deformable discharge pressure responsive means to urge a sidesurface of said unit in sealing engagement with the opposite side wallwhereby said high pressure discharge zone is effectively sealed.

25. A gear pump comprising a pump casing providing a pump cavity havingmeshing gears rotatable therein and having intake and discharge passagescommunicating therewith, said gears in part defining a high. pressuredischarge zone of said cavity at the meshing teeth thereof, saiddischarge zone being further defined by a unit including a pair ofconcave arcuate sealing surfaces adapted to engagethe peripheries ofgear teeth approaching said zone, a plunger, means for moving saidplunger into contact with said unit to move the sealing surfaces thereofinto engagement with the peripheries of said gear teeth, resilient meansfor resisting movement of the sealing surfaces and plunger away from theperipheries of said gear teeth, said means for moving the plungercomprising a sleeve threaded on said plunger and a fixed abutment on thecasing against which the sleeve is adapted to bear, said resilient meanscomprising casing and aspring compressed the second abutment, andopposed side walls in sealing engagement with the sides of saidgears,one of said side walls including deformable discharge pressureresponsive means to urge a side surface of said unit in sealingengagement with the opposite side-wall whereby said high pressuredischarge zone is effectively sealed.

References Cited in the file of this patent UNITED STATES PATENTS

